REAL ESTATE AND OTHER SECURITIES - Narrative (Details)	Sep. 30, 2021 USD ($)
RMBS Designated as AFS
Debt Securities, Available-for-sale [Line Items]
Face amount of securities sold, unsettled	$ 0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration